Shares of PC Mall Inc. fell 6 percent on Friday after the retailer of information technology products reported a fourth quarter loss related to losing business from a large customer.

The El Segundo company late Thursday reported a net loss $393,000 (-3 cents a share), compared with net income of $3.9 million (32 cents) in the same period a year earlier. Net sales fell 8.4 percent to less than $390 million.

PC Mall said it saw a $48.5 million decrease in sales to promotional companies that was related to a large vendor changing its program. In addition, the company took a goodwill write-down of about $800,000 related to plans to unify its commercial brands, which will lower the value of an existing trademark.

“Over the past several years, our company has grown into a multi-billion dollar enterprise in part through our acquisition and internal cultivation of different brands,” Chief Executive Frank Khulusi said in a statement. “We have historically differentiated those brands primarily based on who their customers were. After careful examination of the markets we serve and the trends taking shape in the marketplace, (we) determined that … our commercial customers can benefit from a more unified and streamlined brand strategy.”

In a separate announcement, PC Mall said Mark McGrath had been hired as president, a title previously held by Khulusi, who also is chairman. McGrath most recently was president of Arrow Electronics Inc.’s Arrow S3 subsidiary, which provides voice-over-Internet-protocol technology.

Shares were down 39 cents, or 6.2 percent, to $5.88 on the Nasdaq after earlier falling more than 10 percent.